In typical industrial and manufacturing facilities, various types of machinery are employed at various stages of the production process. Such machines generally function to provide the power and moving forces necessary to achieve the end product or process. From a production viewpoint, it is desirable to maintain the machinery in good operating condition to avoid unproductive downtime and profit loss when a machine experiences a failure condition. Therefore, a typical plant maintenance program will involve activities for monitoring the operating condition of plant machinery so that the health and condition of the machines can be maintained at high levels to reduce the number of unexpected machine failures.
Portable instruments are often employed to periodically monitor various operating conditions of industrial machinery. These portable instruments, which are often referred to as data collectors or data analyzers, typically include a vibration transducer attached to what is essentially a hand-held computer. The maintenance technician places the vibration transducer against a predefined test point of the machine. The resultant machine vibration signal produced by the transducer is provided to the data collector where the data is processed and stored for later downloading to a host computer. The host computer then analyzes the vibration data for faults or other anomalous conditions.
Machines within a facility are typically monitored according to a route which is programmed into the data collector by the host computer. The route will typically include a list of machines, test points, and a set-up condition for each test point. There may be as many as thirty or more machines in the route with ten test points on each machine, and for each test point there may be specified a vibration frequency range to be analyzed, a type of analysis to be performed, a particular type or set of data to be stored, and similar other parameters. In response to commands from the user, the hand held instrument prompts the user for the identity of the machine and the test point to be monitored, and it automatically sets up the instrument, for example, to accept the specified frequency range for the test point, perform the specified analysis and store the specified type or set of data. A Fast Fourier Transform analysis may be performed on a pre-selected frequency range of the data and all or part of the resulting frequency spectrum may be stored and displayed. As the user progresses through the thirty machines and the corresponding 300 test points, he collects and stores vibration data which is subsequently transferred to the host computer for long term storage and further analysis.
The present invention provides a completely new approach to machine monitoring. Instead of manually collecting machine data with a portable device of the type described above, this invention contemplates a machine monitor which is attached directly to the machine or at some point sufficiently proximate the machine to enable the monitor to sense a machine operating characteristic. The monitor includes the electronics and sensors necessary to sense, analyze, and store one or more of the machine's operating characteristics, including vibration, temperature, and flux. Since the monitor and the machine to which it is attached are often located in harsh industrial environments, the monitor's electronics and sensors should be adequately protected from mechanical shock, thermal shock, moisture, oil, dirt, and other environmental elements in order to function reliably over extended periods of time. Moreover, maintenance considerations for such machine monitors dictate that the monitor should be easy to install and replace, and that the monitor's electronics, sensors, and batteries be easily accessed. Provisions should also be incorporated into the monitor to enable maintenance personnel to easily download machine data stored by the monitor and to upload new programming to the monitor when needed.
Another desirable aspect for machine monitors which are powered by internal batteries is low electrical power consumption to enable monitoring of the machine for prolonged periods of time. If the power source for the monitor is quickly depleted, important machine operating data such as temperature, speed, flux, and vibration may be lost and the monitor will be unable to determine the operating condition of the machine. Thus, it is desirable to incorporate into battery-powered machine monitors power saving features such as disabling circuitry within the monitor when the circuitry is not needed for data readings, powering only elements of the monitor which process data readings, and operating the monitor electronics at low clock speeds when possible.